DE19933009A1 - Electric motor e.g. for automobile air conditioning unit, has rotor core provided with slits for reception of internal permanent magnets with non-magnetic section between each permanent magnet and rotor periphery - Google Patents

Abstract

The electric motor has a stator core (21) with a number of stator teeth (25) connected together via a stator yoke (23) and a rotor (10) with internal permanent magnets (13,15), fitted into slits (14,16) in the rotor core (11) adjacent its periphery, with a non-magnetic section (30) between the end of each permanent magnet and the rotor periphery. An Independent claim for a drive employing a permanent magnet electric motor is also included.

Description

The invention relates to an in air conditioning, industrial len devices and electric bicycles used Drive motor and in particular a motor structure that used a rotor core with internal permanent magnets and not just the magnetic torque, but also uses the reluctance torque, so that a motor with higher efficiency can be obtained.

A high-efficiency motor that can utilize both magnetic torque and reluctance torque by embedding internal magnets in a rotor core is well known and is disclosed, for example, in JP H08-331823-A. Fig. 18 is a cross sectional view for explanation of such a motor.

In Fig. 18 an annularly formed stator 401 contains a plurality of teeth 403 and a yoke 405 which connects the roots of several teeth. A plurality of slots 407 formed between the teeth 403 are wound with a three-phase winding.

A rotor 410 is substantially coaxial with the stator 401 , shaped substantially like a cylinder, and faces an inner wall of the stator 401 via an annular intermediate space. The rotor 410 has four rotor poles and is supported by a bearing (not shown) so that the rotor 410 can rotate on a shaft 421 . Four slots 413 are provided on the rotor 410 , which are axially recessed and are arranged at equal intervals in the direction of rotation of the rotor core 411 ; A plate-like permanent magnet 415 is inserted into each slot. At each axial end of the rotor core 411 , an end plate (not shown) is arranged, with which the permanent magnets 415 are attached. The end plate is attached to the end face by a rivet pin 425 which extends through a bore 423 , whereby the permanent magnet 415 is attached to the rotor core 411 . An outer wall of the rotor 410 has notches 419 at the interfaces between the respective rotor poles, both longitudinal ends of the permanent magnet 415 adjoining corresponding notches 419 . An electric current flows through the stator coil to generate a rotating magnetic field. Thereby, the teeth 403 of the stator 401 are alternately attracted and repelled by the rotor poles, whereby the rotor 410 rotates.

In the above structure, the relationship between inductors Ld and Lq is as follows:

Ld <Lq

where Ld is an inductor along the d-axis which is the Rotor pole crosses vertically, and Lq an inductance along of the q axis, which is defined by the interface between the Rotor poles runs.

In general, the engine torque T is given by the following equation:

T = Pn {ψa.I.cosβ + 0.5 (Lq - Ld) I ² .sin2β}

where Pn is the number of pairs of rotor poles, ψa the ver chained magnetic flux is, I is the stator coil current and β the leading phase angle of the current I (electrical angle).

In the above equation, the first term represents that magnetic torque while the second term is that Reluctance torque represented. Because the relationship Ld <Lq is satisfied, the winding current in the manner controlled that the phase of the winding current I related  to the voltage induced in each wick generation is generated, which leads to β being greater than zero (β <0) and the reluctance torque is generated. If β is set to a predetermined value, with the same current a larger torque T than in the case where only the magnetic torque is available, be generated.

However, in the above structure, since the high permeability steel portion 417 is provided between the slits 413 and the notch 419 , a magnetic flux flows through the magnetic path 430 of the steel portion 417 at the end of the permanent magnet 415 . Therefore, the magnetic flux is short-circuited as shown in Fig. 18, although it should reach the stator 401 and should contribute to the torque production. In other words, the magnetic flux decreases by the shorted amount, thereby lowering the motor efficiency. Furthermore, the magnetic flux resulting from the short circuit increases an intermittent torque, whereby noise and vibration of the motor are increased.

Another motor is known from JP H08-331783-A, which uses internal permanent magnets and is shown in FIG. 19. This motor, which differs from the motor described above, has no notches on the outer wall of the rotor, and a method for distributed winding is used for the winding of the stators.

In Fig. 19, a rotor 503 has four groups of internal permanent magnets 501 and 502 in a rotor core 507 which is made of stacked electromagnetic steel sheets. The magnets 501 and 502 are arranged at each pole in the radial direction with a gap. Each group of magnets 501 and 502 is arranged so that the S poles and the N poles are contiguous. The magnets 501 and 502 , which form a layer structure, are arranged so that the outer sides of the respective outer magnets 501 , which are facing the outer edge of the rotor 503 , have the same polarity as the outer sides of the corresponding inner magnets 502 . The magnets 501 and 502 are arcuate, their apexes pointing towards the rotor center, the two magnets essentially forming concentric circles in the layer structure and lying parallel. The space between the two magnets is essentially constant.

The rotor 503 , which is defined as above, rotates by the torque composed of the magnetic torque and the reluctance torque: The magnetic torque is determined by the relationship between the magnetic field of the magnets 501 and 502 and the rotating magnetic field, which in turn is caused by the Generating current that flows through a group of coils 509 that span a predetermined number of teeth 506 defined by broken line 517 ; on the other hand, the reluctance torque is generated by magnetic paths which are formed by the rotating magnetic field and are present both between the magnets 501 and 502 and on the surface of the rotor 503 . Thus, the reluctance torque is used, whereby a motor is realized which has a higher efficiency than the motor using only the magnetic torque.

For motors that use internal permanent magnets have been proposed, not just efficiency increase but also decrease the size of the engine by using a procedure for concentrated wrapping the teeth of the stator is executed with higher density.  

In a conventional motor with concentrated winding however, an adjacent magnetic pole becomes one opposite pole if the motor with a three-phase sen-120 ° current is fed, causing the winding vol Concentrate on one tooth for one pole and one phase is trated. The magnetizing force is therefore double as large as that of the motor with distributed winding, which is why a magnetic flux between neighboring ones Teeth flow, causing the internal permanent magnets be demagnetized.

The invention has for its object the above to solve problems written and an engine with stabi lem drive torque to create.

This object is achieved by an engine according to claim 1.

In the engine according to claim 1, the demagnetization can tization field caused by the magnetic flux magnetic sections flow, causing the demagneti limited at the ends of the permanent magnets can be. In particular, part of the slot in close to the circumference of the rotor core of the demagnetization subjected; the magnetic flux due to the teeth however, demagnetization affects the permanentma due to the presence of the non-magnetic Section hardly. The engine of the invention can thus Demagnetization at the ends of the respective magnets restrict, creating a stable drive torque is created.

According to a feature of the invention, an engine is based on Claim 2 created with which the noise and Schwin conditions can be reduced during its rotation.  

According to yet another feature of the invention an engine according to claim 16 created.

In the motors according to claim 5 or claim 16, the Leakage flow between the rotor poles can be reduced, further can eliminate the imbalance in the radial direction be created and a pseudo skew. in the Result can reduce noise and vibration become.

According to yet another feature of the invention created a drive device according to claim 25, the use an engine according to any one of claims 1, 5 or 16 det.

The drive device according to claim 25 consumed less energy, small in size and suitable for driving a compressor, for example an air conditioner mounted in an electric vehicle. The drive device is also suitable because of its small size, light weight and large Range with one battery charge for driving one Electric bike.

Further developments of the invention are in the dependent Claims specified.

Further features and advantages of the invention will become clear Lich more useful when reading the following description Designs referring to the attached drawing takes; show it:

Fig. 1 is a cross sectional view of a motor according to a first exemplary exporting tion of the invention;

Fig. 2 is a view of a stator of the motor of Fig. 1;

Fig. 3 is a cross-sectional view of an engine according to a second exemplary embodiment of the invention;

Fig. 4 is a view for explaining the relationship between the speed and the motor efficiency of the motor of Figure 3 with concentrated winding or with distributed winding.

Fig. 5 is a view for explaining the relationship between the speed and the loss of the engine according to Fig 3 with concentrated winding or with distributed winding.

Fig. 6 is an exploded perspective view of a motor rotor according to a third exemplary embodiment of the invention;

Fig. 7 is a cross sectional view of the rotor of Fig. 6;

Fig. 8A-D views for explaining the func on principle of the rotor of Fig. 6;

Fig. 9 is an exploded perspective view of a motor rotor according to a fourth exemplary embodiment of the invention;

FIG. 10A-D are cross sectional views of the rotor according to Fig. 9;

. Figs. 11A-D views for explaining the functi onsprinzips of the rotor of Figure 9;

FIG. 12 is an exploded perspective view of a motor rotor according to a fifth exemplary embodiment of the invention;

FIG. 13A-D are cross sectional views of the motor of Fig. 12;

FIG. 14 is an exploded perspective view of a motor rotor according to a fifth exemplary embodiment of the invention;

FIG. 15A, 15B are cross sectional views of the motor of Fig. 14;

FIG. 16 is a cross-sectional view of a compres sor-drive unit of a trofahrzeug in a Elek installed air conditioning accelerator as a seventh exemplary exporting tion of the invention;

FIG. 17 is a cross-sectional view of a drive unit on an electric vehicle accelerator as an eighth exemplary exporting tion of the invention;

Figure 18 is the previously mentioned cross-sectional view of a motor employing a rotor having permanent magnets inter NEN. and

Fig. 19, the above-mentioned cross-sectional view of a motor employing a rotor having another internal permanent magnet.

Version 1

FIG. 1 is a cross-sectional view showing a motor according to a first exemplary embodiment, while FIG. 2 is a view of a stator of the motor of FIG. 1.

In Fig. 1, the motor includes a rotor 10 and a stator 20 which faces the rotor 10 through an annular space. The stator 20 contains a plurality of teeth 25 and a stator core 21 with a yoke 23 connecting the teeth 25 and windings 27 which are provided on the respective teeth 25 according to a method for concentrated winding. The rotor 10 contains the following elements: four groups of permanent magnets 13 and 15 , which are spaced apart in a layer structure; a rotor core 11 comprising stacked electromagnetic layers, each group of permanent magnets 13 and 15 being embedded in corresponding rotor poles in the radial direction of the rotor. Each group of magnets 13 and 15 is arranged in such a way that the S-pole and the N-pole adjoin one another. The magnets 13 and 15 in the layer structure are arranged so that the respective outer sides of the magnets 13 , which face the outer edge of the rotor, have the same polarity as the outer side of the magnets 15 , which are closer than the magnets 13 to the rotor shaft are arranged.

The magnets 13 and 15 are ferrite magnets, so that they can be easily formed in an arc shape. The Magne th 13 and 15 are embedded in slots 14 and 16 which extend in the vicinity of the outer wall of the rotor 10 . The ends of the slots 14 and 16 , ie those sections from the slots that are closest to the outer wall of the rotor 10 , form the non-magnetic cavities 30th The cavities 30 are formed only at the ends of the slots 14 and 16 . The magnets 13 and 15 are thus in contact with the rotor core 11, with the exception of their ends, which face the cavities 30 , so that the magnetic flux from the magnets 13 and 15 can flow evenly. The magnets 13 and 15 are bogenför shaped, with their apexes pointing to the rotor center, furthermore the two magnets 13 and 15 form essentially concentric circles in the layer structure and are parallel to one another. The space between the two magnets 13 and 15 is essentially constant.

A rotor shaft 17 runs through the center of the rotor core 11 , and end plates (not shown) are fastened to the two end faces of the rotor 10 by rivet pins 19 .

The operation of the engine with the above structure is described below. The rotor 10 is rotated in the direction R shown in Fig. 1 by the torque formed from the magnetic torque and the reluctance torque: The magnetic torque is determined by the relationship between the magnetic field of the magnets 13 and 15 and the rotating magnetic field by the Generating current flowing through a group of coils 27 provided on corresponding teeth 25 of the stator 20 ; on the other hand, the reluctance torque is generated by magnetic paths which are formed by the rotating magnetic field and are present on the surface 311 of the rotor 10 , in the space 312 between the magnets 13 and 15 and in the space 313 between the poles. In this case, the reluctance torque complements the magnetic torque, the magnetic torque being generally greater than the reluctance torque.

The concentrated windings 27 , which are provided on the respective teeth 25 , have a utilization rate which is approximately 10% lower than the distributed windings, and therefore the number of wire windings must be increased by approximately 10% compared to that of the distributed windings. However, even with an approximately 10% increase in the number of windings, the wire winding resistance can be significantly reduced compared to that of the distributed windings due to the following factors: (1) the height of the coil end is 40% lower than that of the distributed winding; (2) The span length 29 of the coil spans the width of only one tooth, on the other hand, a span length 517 of the distributed winding in a four-pole rotor covers approximately a quarter of the circumference in the center of the stator, as shown in FIG. 19. Therefore, if a motor with a smaller thickness of the rotor core 11 has to be used because of a limited space, the concentrated winding is preferred because the wire winding resistance can be reduced considerably, whereby the copper loss is significantly reduced and thus the efficiency of the motor is increased.

Since in this first embodiment the magnet end is subjected to demagnetization, non-magnetic cavities 30 are provided at the ends of the magnets 13 and 15 . The cavities 30 formed between the magnet ends and the outer wall of the rotor 10 can form a flow barrier for the magnetic paths short-circuiting the adjacent poles of the rotor 10 and thus limit the magnetic flux short circuit. The magnetic flux between adjacent teeth passes through the cavity 30 , whereby the demagnetizing field via the magnets 13 and 15 is reduced. Instead of forming the cavities 30 , a non-magnetic material such as a resin may be embedded. In this case, the strength of the rotor 10 can be increased.

As shown in FIG. 2, the stator core 21 is divided into teeth 25 , which teeth 25 , after being wound with a coil, are built into the stator 20 by press fitting or welding. This manufacturing method enables the coil to be wound easily and with high density. Furthermore, a wire with high conductivity can be used for the winding of the teeth 25 , whereby the wire winding resistance is significantly reduced.

The following are two motors that have the same value of an induced voltage, compare with each other Chen, wherein a motor has a distributed winding and the other motor has a concentrated winding points. The comparison shows that in this case the Number of turns of wire per phase of the concentrated Winding compared to 110% and the coil diameter 103% the number of turns or the coil diameter of the ver divided winding is, the line wi the level of the concentrated winding is only about 60% the distributed winding.

In a motor with a concentrated winding, in which the Thickness of the stator core about half the size Stator diameter is the total length of the motor including the coil ends by approximately 25% less than that of a distributed winding motor. The Ratio of the number of teeth to the number of poles is appropriately 3: 2.

In the motor according to the first exemplary embodiment, non-magnetic portions, ie cavities 30 , are provided between the outer wall of the rotor 10 and the ends of the magnets 13 and 15 . With this arrangement, a magnetic flux generated by the demagnetizing field existing in the volume between adjacent teeth 25 can be prevented from flowing to the ends of the magnets 13 and 15 . Further, the presence of the non-magnetic portions enables the magnets 13 and 15 to be spaced from the outer wall of the rotor 10 so that the magnetic flux flowing between the adjacent teeth affects the magnets 13 and 15 less. The non-magnetic section is arranged between the outer wall of the rotor 10 and the ends of the two magnets 13 and 15 . With this arrangement, it is unnecessary to elongate the magnets near the outer wall of the rotor, and the rate of protrusion of the poles is approximated to the rate of the rotor where the magnets extend near the outer wall of the rotor. The rate of protruding poles is defined by Ld / Lq (inductance along the d axis to inductance along the q axis).

In other words, the comparison of a conventional motor in which permanent magnets extend near the outer wall of the rotor with the motor of the invention in which non-magnetic portions are formed at the ends of the magnets gives the following result:
The conventional motor undergoes demagnetization at the ends of the magnets, reducing the volume of the magnetic flux from the initial stage, thereby changing the output torque. The motor according to the first embodiment of the invention, on the other hand, is not influenced by the demagnetization, since the non-magnetic sections are formed at the ends of the magnets, so that a magnetic flux with a constant volume and a stable torque can be expected.

Version 2

Fig. 3 is a cross-sectional view of an engine according to a second exemplary embodiment of the invention. In Fig. 3, the rotor 31 contains the following elements: four plates made of permanent magnets 35 and a rotor core 33 which comprises stacked electromagnetic layers. Each permanent magnet 35 is embedded in the rotor core 33 transversely to the radial direction of the rotor. Each magnet 35 is arranged in such a way that the S pole and the N pole are adjacent to one another. Non-magnetic sections 37 are formed at the ends of the respective magnets 35 in order to limit the demagnetization due to the magnetic flux flowing between the adjacent teeth 25 . The magnet 35 contains a rare earth magnet, the residual magnetic flux density of which is 1.1 to 1.4 T (Tesla).

The operation of the rotor with the above structure is described below. The rotor 31 is rotated in the direction R shown in FIG. 3 by the torque formed from the magnetic torque and the reluctance torque: The magnetic torque is determined by the relationship between the magnetic field of the magnets 35 and the rotating magnetic field generated by the current is generated which flows through a group of coils 27 provided on the respective teeth 25 of the stator 20 ; on the other hand, the reluctance torque is generated by magnetic paths 321 and 323 , which are formed by the rotating magnetic field and are present on the surface of the rotor 31 and in the space between the poles.

Since the magnet 35 uses a rare earth magnet, it generates a larger volume of magnetic flux than a ferrite magnet. The thickness of the rotor core 33 can be reduced by 20-60% compared to that of the ferrite core. Furthermore, a lower height of the coil end is realized with the method for concentrated winding than with the method for distributed winding. As a result, a motor with smaller axial dimensions than the conventional motor can be achieved. Since the magnet 35 is plate-shaped, low manufacturing costs can be expected.

Fig. 4 shows the relationships between the speed and the efficiency of the motor according to the second embodiment with concentrated winding or with distributed winding. In Fig. 4, a solid line indicates the relationship between the speed and the efficiency of the concentrated winding motor according to the second embodiment. The broken line indicates the relationship between the number of revolutions and the efficiency of the motor in which the same rotor as in the motor described above is used, but a distributed winding stator is used which is such that an induced voltage and a magnetic core flux density are generated, each corresponding to those of the above-described motor. The two lines represent the values measured at the same load torque. The motor according to the second embodiment shows an increase in efficiency of 0.5-2% compared to the motor of the concentrated winding type, and the difference in efficiency increases at lower speeds.

Fig. 5 shows the relationships between the speed and the loss in the concentrated windings under the same conditions as described above. In FIG. 5, the copper loss is approximately constant at the same torque regardless of the speed; however, the iron loss increases in proportion to the speed.

Therefore, the copper loss at low speed, at the iron loss is small, a bigger influence so that the difference in efficiency between the concentrated winding and the distributed winding increases.

In general, the power supply frequency for the Achieving the same speed with a larger number from Poland to. On the other hand, there is iron loss an eddy current loss and a hysteresis loss. The Eddy current loss is proportional to the square of the frequency tional, while the hysteresis loss is proportional to the frequency is tional.

In the second embodiment, the increase in Iron loss the decrease in copper loss when the Number of rotor poles is at least six, which makes the Efficiency is reduced. If the rotor has two poles the electrical angles between the N- Pole and the S pole 120 ° and 240 °, the attraction force of the rotor to the adjacent section of the N and S Pole is inclined, with both poles on the stator through the electrical current are generated. Then the rotor points problematic eccentricity. Therefore in the second version uses four poles in the rotor. in the In the case of four poles, there are two pairs from N and S poles available that are well balanced. With regard Efficiency, noise and vibrations of the engine the four-pole rotor is the best choice. Also would arcuate magnets a larger volume of the generate magnetic flux and another size ver allow the engine to be reduced.

The construction of the rotor 31 according to the second embodiment is explained in more detail below. The rotor core 33 contains the axially stacked rotor core layers with the same shape, which are made of electromagnetic steel layers. Four-plate type permanent magnets are embedded in the rotor core 33 perpendicular to the radial direction of the rotor. All magnets lie side by side in such a way that the S poles and N poles alternate. At the ends of the respective magnets 35 non-magnetic sections 37 are provided in order to limit the demagnetization due to the flux between the adjacent teeth 25 .

The non-magnetic portion 37 represents an elongated hole 37 or a cavity drilled in contact with the ends of the corresponding magnets 35 . The elongated holes 37 are connected to the slots 34 , on which the permanent magnets are arranged, and the shape of the holes 37 is the same through the entire thickness of the rotor core. At both ends of the rotor core (not shown) end plates are arranged, which are fastened with rivet pins 19 extending through the holes, so that the rotor core 33 itself can be fastened and also the magnets 35 can be fastened in the rotor core 33 . The rotary shaft 17 is press-fitted into the rotor core center, the rotor 31 rotating on the shaft 17 .

With the embedded magnets 35 in the rotor core 33 , tubes made of stainless steel can be omitted, which previously covered the outer wall of the rotor, to prevent the permanent magnets from falling out of the outer wall of the rotor core. This omission can reduce the magnetic space between the rotor and stator and also reduce the loss due to the eddy current in the tube. Furthermore, the construction according to the second embodiment generates a usable reluctance torque. By virtue of these advantages, the motor according to the second embodiment of the invention can be highly efficient.

In this second embodiment, the rotor 31 is difficult to skew, particularly when sintered magnets are embedded in the rotor core 33 . In this case, there is no way to make the rotor skew, but the slot 34 can be widened. The skewing of the rotor reduces noise and vibrations during rotation and is aimed as follows: In order to form the rotor core 33 , rotor core layers are stacked on top of one another in such a way that they are shifted in the circumferential direction on the shaft 17 by a small angle to one another. If the slots 34 are widened with respect to a skew of the motor, voids are created between the pole faces of the corresponding magnets 35 and the rotor core 33 , which reduce the permeability. This lowers the engine's efficiency. As described above, the second embodiment of the invention still has problems in noise and vibration; however, these difficulties are overcome by the following exemplary explanations.

Version 3

Fig. 6 is an exploded perspective view of a rotor of a motor according to a third exemplary embodiment. FIG. 7 is a cross sectional view of the rotor shown in FIG. 6. Fig. 8 shows the principle according to which the intermittent torque and a torque ripple are eliminated.

For the motor shown in FIGS . 6 to 8, electromagnetic steel plates are punched out circularly, these circular rotor core layers being stacked on top of one another to form the rotor cores 51 , 53 , 55 and 57 . Permanent magnets 121 are embedded in these rotor cores. Non-magnetic elongated holes 61 , 63 , 65 , 67 , 71 , 73 , 75 and 77 are provided in contact with the ends of the magnets 11 . The rotor designed in this way has four poles.

When the rotor rotates in the R direction shown in FIG. 7, the elongated holes 61 , 63 , 65 and 67 in the direction of rotation of the rotor form an angle θ _j with a pole boundary. The angle θ _j takes four values, the number of stator slots (teeth) of the stator is 12 (3 × number of poles = 4), and a distributed winding is also used. Thus θ _j assumes the values 3.75 °, 11.25 °, 18.75 ° and 26.75 °. The rotor cores 51 , 53 , 55 and 57 are stacked one on top of the other so that they are each shifted by 90 ° to one another. The total thickness of the rotor is distributed approximately one quarter each to the individual rotor cores.

The jth rear elongated hole 71 , 73 , 75 or 77 forms an angle θ ' _j to the pole boundary. The angle θ ' _j has the values 26.25 °, 18.75 °, 11.25 ° and 3.75 °. Hence the relationship: θ _j + θ ' _j = 30 °. The slots at the rear are defined as follows: A slot at the back of a rotor pole is followed by the slot at the front of the following rotor pole in the direction of rotation. If the rotor cores 51 , 53 , 55 and 57 are stacked one on top of the other, the forward elongated holes or the rearward elongated holes of a pole can have four different shapes in the direction of rotation. The values assumed by θ _j and θ ' _j do not necessarily follow the sequence described above.

The principle according to which the torque ripple is reduced is now explained with reference to FIGS . 8A-D. FIGS. 8A-D show relationships between the slot and the tooth sition on a pole boundary at the same Rotorpo. In Fig. 8A, the magnetic flux supplied from the pole face 135 to the teeth 131 of the stator moves along the elongated hole 65 in the direction of rotation. However, the stator slots 133 have a large magnetic resistance.

The spatial relationship between the elongated holes 61 , 63 , 65 and 67 and the stator slots is available for the same rotor position in four ways. In other words, the tips of the respective elongated holes define approximately a quarter of each space between adjacent teeth. Therefore, the magnetic flux running from the tips of the respective elongated holes to the teeth moves every 7.5 °, ie 360 ° / (number of teeth = 12 × 4) = 7.5 ° past the stator slot. If all the elongated holes had the same shape, the magnetic flux moving from the tips to the teeth would move past the stator slot after every 30 °, ie 360 ° / (number of teeth = 12) = 30 °. This third embodiment therefore generates a fourfold ripple compared to the rotor with the same shape of the elongated holes. Therefore, the amount of ripple is reduced to about a quarter.

From JP H09-195379-A, which also reads to the applicant, it is known that when the relationship θ _j + θ ' _j = 30 ° applies, the torque becomes maximum and the intermittent torque (cogging torque) becomes minimal. This application also teaches that the presence of the elongated holes can reduce the flow volume that shorts a positive pole face with a negative pole face. The construction of the third exemplary embodiment enables a single shape for the rotor core position to be sufficient, which saves punching tool costs, and an increase in the number of magnets can be reduced by the rotor provided with the pseudo skewing, as a result of which noises and vibrations be reduced.

In this embodiment, the pole boundary is defined for the same size, ie 90 °, and the teeth are arranged with the same gaps. The elongated hole, θ _j or θ ' _j assumes minimum values, can accommodate a magnet in the elongated hole.

The magnetic flux can exit at both ends of the rotor in the axial direction, which is why the rotor cores 51 and 57 arranged at the ends of the rotor should expediently be made somewhat thicker than the other cores 53 and 55 . The difference in thickness between these two types of rotor cores is suitably not less than 0.5 mm when dimensional errors of the stacked thickness and the magnet shape are taken into account, and suitably not more than 2.5 mm when the leakage flow volume is taken into account.

Version 4

Fig. 9 is an exploded perspective view of a rotor of a motor according to a fourth exemplary embodiment of the invention. FIG. 10A-D are cross-sectional views of the rotor shown in Fig. 9. Furthermore, the Fig explained. 11A-D, the principle according to which the intermittent torque and the torque value can be reduced for the same rotor.

As for the construction and the operation of the fourth embodiment, the description of the same content as in the third embodiment is omitted. In the third embodiment described above, an elongated hole of the rotor core has the shape shown in FIG. 7. In the fourth embodiment, four rotor core shapes are available, ie a rotor core 81 , 83 , 85 or 87 with corresponding shapes of the elongated holes. The number of stator slots (number of teeth) is 6, ie 3/2 × (number of rotor poles = 4), and a method for concentrated winding is used.

The four poles have the same elongated hole shape in the direction of rotation in the corresponding rotor cores. Now it is assumed that the rotor rotates in the direction R shown in Fig. 10A. If the front elongated holes 91 , 93 , 95 and 97 form an angle θ _i with respect to a pole boundary, this angle θ _{i takes} four values, ie θ _i = 3.75 °, 11.25 °, 18.75 ° and .26.25 °. The rear slots 101 , 103 , 105 and 107 form an angle θ ' _i with respect to the pole boundary. This angle θ' _i takes the values 26.25 °, 18.75 °, 11.25 ° and 3.75 ° on. Hence the relationship θ _i + θ ' _i = 30 ° applies. The rear holes described above are defined as follows:
A slot at the rear of a rotor pole is followed by the slot at the front of a subsequent rotor pole in the direction of rotation. At a corresponding stack thickness of the rotor core 81 , 83 , 85 , 87 accounts for approximately a quarter of the total rotor thickness.

When these rotor cores are stacked on top of each other, four shapes are available for the front elongated holes or the rear elongated holes of a rotor pole in the direction of rotation of the rotor. The values assumed by θ _i and θ ' _i do not necessarily follow the sequence described above. In other words, θ _i takes the values 26.25 °, 18.75 °, 11.25 ° and 3.75 ° in this order in the fourth embodiment; however, the order can be changed as required. The shape patterns are not limited to the four patterns mentioned above, but the number can be increased to lower the torque ripples more.

The principle according to which the torque ripple is reduced will now be described with reference to FIGS. 11A-11D. These figures illustrate relationships between the elongated hole and the teeth at the same rotor position. In Fig. 11A, the magnetic flux supplied from the pole face 137 moves to the teeth 111 or 115 of the stator along the elongated hole 97 in the direction of rotation R. However, the stator slot 119 has a large magnetic resistance. Similarly, the magnetic flux supplied from the pole face 138 of the Long moved to the teeth 113 along the hole 97 in the direction of rotation R. The spatial relationship between the teeth and the elongate hole 97, which are connected to the pole face 138 in contact, is opposite the räumli Chen Relationship between the teeth and the elongated hole 97 , which are in contact with the pole face 137 , pushed ver by 30 °.

In the manner described above, eight patterns are available in the spatial relationship between the stator slots and the elongated holes 91 , 93 , 95 and 97 at the same rotor position. The tips of the respective elongated holes define an eighth of the respective angular extent of 60 ° between the adjacent teeth. Therefore, the flux emanating from the top of the elongated hole moves past the stator slot every 7.5 °.

The fourth version creates four times more wavy than in the case where the rotor has elongated holes has the same shape and the river turns every 30 ° moved past the stator slots. Hence the Ripple amount reduced to about a quarter.

From JP H09-195379-A of the applicant it is known that when θ _i + θ ' _i = 30 ° is satisfied, the torque becomes maximum and the intermittent torque becomes minimum. In addition, this application teaches that the presence of the elongated holes can reduce the flow volume that shorts a positive pole face with a negative pole face.

Because the elongated holes on the same core layer have the same shape possess, there is no imbalance in the radial direction on.

Version 5

Fig. 12 is an exploded perspective view of a rotor of a motor according to a fifth exemplary embodiment of the invention. FIG. 13A-D are cross-sectional views of the same rotor.

As for the construction and functioning of the fifth Execution concerns, the description of the same Contents as in the fourth embodiment omitted.

In this version, a four-pole rotor with notches 151 , 153 , 155 and 157 is used. The notches are provided at those points on the rotor circumference where the distance to the ends of the permanent magnets 121 is the smallest.

Depending on the locations of the notches, four types of rotor cores 141 , 143 , 145 and 147 are available, as shown in Figures 13A-D. The number of stator slots (= number of teeth) is 6 or 12, ie (3/2) × (number of poles = 4) or 3 × (number of poles = 4).

The locations of the notches are on the same rotor core with respect to the front side and the back side of the Rotor poles in the direction of rotation are the same for all four poles.  

Assuming that the rotor rotates in the direction R as shown in Fig. 13A, the angle θ _{i takes} four values, namely 3.75 °, 11.25 °, 18.75 ° and 26.25 °, the angle θ _{i being formed} by a pole boundary and the edges of corresponding notches 161 , 163 , 165 and 167 lying in the direction of rotation.

The edges of corresponding rear notches 171 , 173 , 175 and 177 form an angle θ ' _i with respect to the pole boundary. The angle θ ' _i takes on the values 26.25 °, 18.75 °, 11.25 ° and 3.75 °. Hence the relationship θ _i + θ ' _i = 30 ° applies. The rear notches described above are defined as follows:
A rear notch of the rotor pole is followed by the front notch of a subsequent rotor pole in the direction of rotation. The respective stack thickness of a rotor core 141 , 143 , 145 and 147 accounts for approximately a quarter of the total rotor thickness.

The fifth embodiment has the same function wise and creates the same advantages as the fourth Execution. The ends are in the fifth version of the respective magnets within the corresponding Notches, reducing the influence of the demagnetizing field is reduced to the respective magnets. This structure thus allows the magnets to be permanently demagnetized resist resistance.

Version 6

Fig. 14 is an exploded perspective view of a rotor of a motor according to a sixth embodiment of the invention. Figs. 15A and 15B are Querschnittsansich th of the rotor for the same engine.

In Fig. 14, permanent magnets 185 and 187 are embedded in rotor cores 181 and 183 . The rotor core contains stacked rotor core layers, which are made of an electromagnetic plate, which are punched out in an approximate circular shape. Langlö cher 195 and 197 are provided, which are in contact with the forward ends of the magnets 185 and 187 in the direction of rotation. The slots 195 and 197 are only provided on two out of four poles of the rotor.

In the sixth embodiment, one magnet per rotor pole is divided into two sections in the radial direction, in other words, the two sections form a layer structure. The respective ends of the outer magnet 185 or the inner magnet 187 extend in the vicinity of the rotor circumference. This arrangement enables both the protruding pole rate and the reluctance torque to increase. This advantage is known from JP H08-331783-A. A gap between the forward ends of the outer and inner magnets is wider than that between the rear ends. This arrangement reduces the flux concentration at a specific location and also reduces iron loss. This advantage is known from JP H08-336246-A.

The sixth embodiment has the following advantage: Assuming that the rotor rotates in the direction of rotation R, as shown in FIG. 15A, the elongated holes 195 and 197 in front form angles θ2 and δ2 with respect to the pole boundary. The outer magnet 185 , the leading end of which defines the angle θ2, forms an angle of 31 °, while the inner magnet 187 , the leading end of which defines the angle δ2, forms an angle of 17 °. The rotor pole adjacent to the above-described rotor pole has no front elongated holes, and the respective ends of the outer and inner magnets, which are located close to the rotor circumference, form angles θ1 and δ1 with respect to the pole boundary. As far as the outer magnet 185 is concerned, the angle θ1 is 23.5 °, whereas, in contrast to the inner magnet 187 , the angle δ1 is 9.5 °. The number of stator slots (= teeth) is 24, ie (6 × number of motor poles = 4), the method being used for distributed winding. The following relationships apply under this condition: θ _j = 16 + 60.j. 2/4 ² and δ _j = 2 + 60.j.2 / 4 ² . The rotor core 183 is rotated 90 ° with respect to the rotor core 181 and stacked thereon. Each of the rotor cores 181 and 183 accounts for approximately half of the total thickness of the rotor.

With the sixth version, the same advantage as can be achieved with the third embodiment.

In the previous exemplary implementations, a four-pole rotor used for the description; the Number of poles, the shapes of the rotor core, the perma Magnets and the stator are not on the in examples used in these statements are restricted. The idea of the invention leaves various modifications to.

Version 7

Fig. 16 is a cross-sectional view of a drive unit of a Kompressoran INSTALLING in an electric vehicle th air conditioner according to a seventh exemplary imple mentation of the invention. The rotor 10 is used in the motor according to the first embodiment. An arc-shaped permanent magnet per pole is divided into two sections in the radial direction, that is to say in the magnets 13 and 15 , which form a layer structure and whose apex points toward the rotor center. The magnets are embedded in the rotor core 11 , and non-magnetic sections are also provided between the respective magnets 13 and 15 and the rotor circumference. Concentrated windings are provided on the corresponding teeth of the stator. The rotor 10 faces the stator 20 via an annular inter mediate space, whereby the motor is formed. This water motor is integrated as a drive in a housing 40 of the compressor.

Not only the engine of the first exemplary version, but also those of the second to sixth versions are applicable to this seventh embodiment, the same functions and advantages as in the ur original versions can be obtained. If a brushless motor that drives a compressor integrated, which may require an airtight envelope the rotor position of the motor with a sensor such as a Hall element is difficult to detect because the Hall Element requires input and output wiring and one resulting from the operation of the compressor subject to high pressure so that accurate detection the position of the rotor is not expected. If so the brushless motor drives the compressor is integrated is a drive without using a Sensors (sensor-free drive) common.

If the concentrated winding is pre-selected on the stator is seen, a large current flows when switched on, so that the rotor is under a strong demagnetizing field could be thrown. However, since the permanent magnets in the rotor are embedded, the strong demagneti be limited that the magnets adversely lig could influence. Furthermore, the engine height will be one finally the coil ends decreased so that a height efficiency is to be expected. The ver this engine turning drive unit is suitable for the compressor  an air conditioner installed in an electric vehicle, for which a low power consumption and a small one and lighter bodies are necessary. If rare earth magne the rotor core can be used further become slim, which is a smaller body of the an drive unit results.

Version 8

Fig. 17 is a cross-sectional view of a Antriebsein unit for an electric vehicle according to an eighth exemplary embodiment. All of the engine designs used in the first through sixth embodiments can also be applied to the structure shown in Fig. 17 to achieve the same functions and advantages.

The structure and operation of the eighth embodiment of the invention are described below. The rotation of the rotary shaft 17 of the motor is transmitted to the output shaft 43 of the drive unit via a gear 41 . The output shaft 43 is connected to pedals of the bicycle (not shown). When a bicycle is supported by an electric motor, the load torque is controlled in response to the cyclist's pedal force, which is why a large torque is required and a speed of 2000 to 5000 min ^{-1 is} required. A motor with a rotor with internal permanent magnets and four poles is the best choice for this application due to the high output power. Since the drive unit is attached to the bicycle, a slim body with low weight is desirable. A motor with higher efficiency would increase the range of the bike with a single battery charge. When the cyclist starts on the bicycle or drives the bicycle uphill, a large amount of electrical support is required, ie the motor is loaded with a strong torque, so that a large current flows through the motor. At this time, a demagnetizing field is generated; however, the internal permanent magnets can prevent exposure to the demagnetizing field. As described above, the motor of the invention is well suited as a drive unit for an electric vehicle.

The invention is not based on the embodiment described above restrictions, but rather shape and specifics tion of the engine can be modified, also a Combination of a drive device and a motor be modified within the inventive concept.

The engine of the invention comprises the following elements:
A stator core comprising a plurality of teeth and a yoke connecting these teeth; Coils wound on the teeth in the form of a concentrated winding; and a rotor with internal permanent magnets. The rotor with internal permanent magnets comprises the following elements:
Rotor cores with several slots, the ends of which extend in the vicinity of the rotor circumference; Permanent magnets located in the slots; and non-magnetic portions provided between the circumference of the rotor cores and the respective ends of the permanent magnets. With this construction, the motor can permanently withstand demagnetization, have a smaller size and still have a high degree of efficiency and can also be produced in a highly efficient manner. The motor can be integrated as a drive in a drive unit. In particular, a device that requires a large power saving and a small and light body, z. B. a compressor of an air conditioning system for an electric vehicle or an electric bike, is a good example of the integration of a rotor with internal permanent magnets in a motor to achieve significant practical advantages.

Claims (27)

1. engine, with

• a) a stator core ( 21 ) which contains a plurality of teeth ( 25 ) and a yoke ( 23 ) connecting the teeth ( 25 ), and
• b) coils ( 27 ) which are wound around the teeth ( 25 ) in the form of a concentrated winding,

marked by

• 1. a rotor ( 10 ) with internal permanent magnets ( 13 , 15 ), which contains:
  • 1. (c-1) a rotor core ( 11 ) with a plurality of slots ( 14 , 16 ), the ends of which extend in the vicinity of the rotor circumference,
  • 2. (c-2) permanent magnets ( 13 , 15 ), which are arranged in the slots ( 14 , 16 ), and
  • 3. (c-3) non-magnetic portions ( 30 ) which are provided between the rotor circumference and the respective ends of the permanent magnets ( 13 , 15 ).

2. Motor according to claim 1, characterized in that the slots ( 14 , 16 ) have an arc shape, of which the apex points to the rotor center. 3. Motor according to claim 1, characterized in that the permanent magnets ( 13 , 15 ) are rare earth magnets. 4. Motor according to claim 1, characterized in that the rotor ( 10 ) has four poles. 5. Motor, with:

• a) a stator core ( 21 ) which contains a plurality of teeth ( 25 ) and a yoke ( 23 ) connecting the teeth ( 25 ), and
• b) coils ( 27 ) which are wound around the teeth ( 25 ),

marked by

• 1. a rotor ( 10 ) with internal permanent magnets ( 13 , 15 ), which contains:
  • 1. (c-1) a rotor core ( 11 ) which is formed from a stack of rotor core layers which are made from electromagnetic steel plates,
  • 2. (c-2) an internal permanent magnet ( 13 , 15 ) which is embedded in the rotor core ( 11 ), and
  • 3. (c-3) a non-magnetic portion ( 30 ) which is in contact with an end face and / or one end of the positive pole and / or one end of the negative pole of the permanent magnet ( 13 , 15 ) or in the vicinity of which is

wherein the plurality of rotor core layers in the rotor core ( 11 ) extend over different angles between a pole boundary and a forward non-magnetic section in the direction of rotation of the rotor ( 10 ). 6. Motor according to claim 5, characterized in that the non-magnetic section is arcuate extends essentially parallel to the rotor circumference. 7. Motor according to claim 5, characterized in that the permanent magnet ( 13 , 15 ), which is embedded in the rotor core ( 11 ), is a solid plate. 8. Motor according to claim 5, characterized in that the permanent magnet ( 13 , 15 ) is rectilinear, is embedded in the axial direction in the rotor core ( 11 ) and does not run obliquely. 9. Motor according to claim 5, characterized in that
the rotor ( 10 ) with internal permanent magnets has N-rotor core layers that form different angles (θ _i ) between a pole boundary and a non-magnetic section of the rotor pole in the direction of rotation of the rotor ( 10 ),
each rotor core layer has approximately the same thickness, and
the following equation applies:
θ _i + θ ₀ + 120.i / (PN)
where P = number of rotor poles, the number of stator slots is either (3/2) × P or 3 × P and θ _{0 is} a constant such that the inequality 0 ≦ θ _i ≦ 120 / P for i = 1, 2,. . ., N is satisfied. 10. Motor according to claim 5, characterized in that
the rotor ( 10 ) with internal permanent magnets has N-rotor core layers that form different angles (θ _i ) between a pole boundary and a non-magnetic section of the rotor pole in the direction of rotation of the rotor ( 10 ),
each rotor core layer has approximately the same thickness, and
the following equation applies:
θ _i = θ ₀ + 60.i / (PN)
where P = number of rotor poles, the number of stator slots is 6 × P and where θ _{0 is} a constant such that the inequality 0 ≦ θ _i ≦ 120 / P for i = 1, 2,. . ., N is satisfied. 11. Motor according to claim 9 or 10, characterized in that the following equation applies:
θ _i + θ ' _i = 120 / P,
where θ ' _{i is} an angle which extends between a pole boundary and a rear non-magnetic section of the i-th rotor core position of the rotor pole in the direction of rotation of the rotor ( 10 ). 12. Motor according to claim 5, characterized in that the internal permanent magnet is formed by stacking one above the other n / P rotor cores, which are each shifted by an angle of 360.j / P to each other, the following equation applies:
θ _j = θ ₀ + 120.jn / P ²
wherein θ _{j is} an angle that extends between a pole boundary and a forward non-magnetic portion of the rotor pole in the direction of rotation of the rotor ( 10 ) and takes P / n different values, each of which is repeated periodically n times; P is the number of rotor poles and the number of stator slots is either (3/2) × P or 3 × P; θ _{0 is} a constant for which the inequality 0 ≦ θ _j ≦ 120 / P for j = 1, 2,. . ., P / n is satisfied; and n is a natural number less than or equal to P / 2. 13. Motor according to claim 5, characterized in that that
the internal permanent magnet by stacking stack of n / p rotor cores that is formed each time an angle of 360.j / P are shifted to each other, where the following equation applies:
θ_j = θ₀+ 60.j.n / P^2nd
where θ_j is an angle between one Pole boundary and an overlying non-magnetic Section of the rotor pole in the direction of rotation of the rotor (10th) extends and P / n takes different values, each of which  is repeated periodically n times; P the number of rotors is pole and the number of stator slots is 6 × P; θ₀  is a constant for which the inequality
0 ≦ θ_j ≦ 120 / P
for j = 1, 2,. . ., P / n is satisfied; and n is a natural number less than or equal to P / 2. 14. Motor according to claim 12 or 13, characterized shows that n is 1. 15. Motor according to claim 12 or 13, characterized in that the following equation applies:
θ _j + θ ' _j = 120 / P,
where θ ' _{j is} an angle extending between a pole boundary and a rear non-magnetic portion of a rotor pole adjacent to the forward non-magnetic portion of the j-th rotor pole in the direction of rotation of the rotor ( 10 ). 16. Motor, with

• a) a stator core ( 21 ) which contains a plurality of teeth ( 25 ) and a yoke ( 23 ) connecting the teeth ( 25 ), and
• b) coils ( 27 ) which are wound around the teeth ( 25 ),

marked by

• 1. a rotor ( 10 ) with internal permanent magnets ( 13 , 15 ), which contains:
  • 1. (c-1) a rotor core ( 11 ) which is formed from stacked rotor core layers which are made of electromagnetic steel plates,
  • 2. (c-2) an internal permanent magnet ( 13 , 15 ) which is embedded in the rotor core ( 11 ), and
  • 3. (c-3) a notch ( 151-157 ) which is provided on the rotor circumference in the vicinity of an end face and / or the end of the positive pole and / or the end of the negative pole of the permanent magnet ( 13 , 15 ),
    

wherein the plurality of rotor core layers between a pole boundary and an edge of a front notch extend in different directions in the direction of rotation of the rotor. 17. Motor according to claim 16, characterized in that
the rotor ( 10 ) with internal permanent magnets has N-rotor core layers, which form different angles (θ _i ) between a pole boundary and the edge of the front notch of the rotor pole in the direction of rotation of the rotor ( 10 ),
each rotor core layer has approximately the same thickness, and
the following equation applies:
θ _i = θ ₀ + 120.i / (PN)
where P = number of rotor poles, the number of stator slots is either (3/2) × P or 3 × P and θ _{0 is} a constant such that the inequality 0 ≦ θ _i ≦ 120 / P for i = 1, 2,. . ., N is satisfied. 18. Motor according to claim 16, characterized in that
the rotor ( 10 ) with internal permanent magnets has N-rotor core layers, which form different angles (θ _i ) between a pole boundary and the edge of the front notch of the rotor pole in the direction of rotation of the rotor ( 10 ),
each rotor core layer has approximately the same thickness, and
the following equation applies:
θ _i = θ ₀ + 60.i / (PN)
where P = number of rotor poles, the number of stator slots is 6 × P and where θ _{0 is} a constant such that the inequality 0 ≦ θ _i ≦ 120 / P for 1 = 1, 2,. . ., N is satisfied. 19. Motor according to claim 17 or 18, characterized in that the following equation applies:
θ _i + θ ' _i = 120 / P,
where θ ' _{i is} an angle that extends between a pole boundary and the edge of a rear notch of the i-th rotor core position of the rotor pole in the direction of rotation of the rotor. 20. Motor according to claim 16, characterized in that
the internal permanent magnet is formed by stacking n / P rotor cores, which are shifted by an angle of 360.j / P to each other, whereby the following equation applies:
θ _j = θ ₀ + 120.jn / P ²
where θ _{j is} an angle that extends between a pole boundary and the edge of a leading notch of the rotor pole in the direction of rotation of the rotor ( 10 ) and takes P / n different values, each of which is repeated periodically n times; P is the number of rotor poles and the number of stator slots is either (3/2) × P or 3 × P; θ _{0 is} a constant for which the inequality 0 ≦ θ _j ≦ 120 / P for 120 / P for j = 1, 2,. . ., P / n is satisfied; and n is a natural number less than or equal to P / 2. 21. Motor according to claim 16, characterized in that the internal permanent magnet is formed by stacking one above the other n / P rotor cores, which are each shifted by an angle of 360.j / P to each other, the following equation applying:
θ _j = θ ₀ + 60.jn / P ²
where θ _{j is} an angle that extends between a pole boundary and the edge of a leading notch of the rotor pole in the direction of rotation of the rotor ( 10 ) and takes P / n different values, each of which is repeated periodically n times; P is the number of rotor poles and the number of stator slots is 6 × P; θ _{0 is} a constant for which the inequality 0 ≦ θ _j ≦ 120 / P for j = 1, 2,. . ., P / n is satisfied; and n is a natural number less than or equal to P / 2. 22. Motor according to claim 20 or 21, characterized shows that n is 1. 23. Motor according to claim 20 or 21, characterized in that the following equation applies:
θ _j + θ ' _j = 120 / P,
where θ ' _{j is} an angle that extends between a pole boundary and the edge of the rear notch of the rotor pole, which is adjacent to the front notch of the new rotor pole in the direction of rotation of the rotor. 24. Motor according to claim 5 or claim 16, characterized characterized that of the stacked several rotor cores the respective thickness of the rotor cores, which are arranged at the two axial ends in order about 0.5 mm to 2.5 mm larger than the thickness of the remaining rotor cores. 25. Drive unit which contains a motor as drive, which comprises:

• a) a stator core ( 21 ) which contains a plurality of teeth ( 25 ) and a yoke ( 23 ) connecting the teeth ( 25 ), and
• b) coils ( 27 ) which are wound around the teeth ( 25 ) in the form of a concentrated winding,

marked by

• 1. a rotor ( 10 ) with internal permanent magnets ( 13 , 15 ), which contains:
  • 1. (c-1) a rotor core ( 11 ) with a plurality of slots ( 14 , 16 ), the ends of which extend in the vicinity of the rotor circumference,
  • 2. (c-2) permanent magnets ( 13 , 15 ), which are arranged in the slots ( 14 , 16 ), and
  • 3. (c-3) non-magnetic portions ( 30 ) which are provided between the rotor circumference and the respective ends of the permanent magnets ( 13 , 15 ).

26. Drive unit according to claim 25, characterized records that it is a compressor one in an elec trofahrzeug installed air conditioning drives. 27. Drive unit according to claim 25, characterized records that she drives an electric bike.